Modern data storage devices require certain data, called “system information”, concerning the configuration and operation of the storage device. System information includes, for example, information concerning zone configuration and the frequency at which user data are stored in various zones, identification of data sectors that are defective, reassignment tables that associate virtual addresses to physical addresses on the storage medium, information concerning the configuration of servo regions between data sectors, etc. System information is used by the data storage device controller to control operation of the data storage device during its operation. Typically, system information is stored in data sectors, known as “system sectors”, reserved for this class of data. Due to its criticality, it is common to store several copies of system information in the system sectors. For example, in magnetic disc drives, it is common to store at least three copies of the drive information. The extra copies are stored to serve as back-up in case of corruption to data and defects growth.
At power on to the data storage device, the system information is read to the device controller to govern operation of the storage device. It is common to perform multiple retries of a single copy of the system information before attempting to read another copy. More particularly, the storage device firmware will trigger the retry scheme to attempt to read back system information from the single copy. If the copy contains uncorrectable data error, all retries in the scheme will be exhausted before the next copy of the system information is attempted to be read. Typically, attempted reading a given copy of the system information is retried a predetermined number of times, 100 or more retries being typical for a given copy of the system information. If reading of that copy is unsuccessful after the predetermined number of retries, the process moves on to the next copy of the system information to attempt to read the next copy. The process continues until either the system information is successfully read, or all copies of the system information cannot be read after attempting to read the data from each copy the predetermined number of retries. While three copies of system information is usually stored in the system sectors, five or more copies of particularly critical system information, such as sector defect lists and the like, might be stored.
These retries require considerable upload time, which is especially adverse where design constraints require the storage device to be ready in a specific period of time. In a worse case scenario, all but the last copy of the storage device information is corrupted, resulting in all retries in the retry scheme being attempted for all of the bad copies before the last good copy is uploaded.
Experiments conducted for measuring the time for uploading system data reveals that each uncorrectable copy of system information may take as much as four seconds to exhaust all the retries in the retry scheme. Consequently, if a system has three copies of system information stored in the area reserved for the system information, and if the first two copies of the system information are corrupted and unrecoverable, the time required to upload the system information will require an additional eight seconds. In most cases, particularly where specifications for the data storage device require a shorter time, the amount of time required for repeating the retries is unacceptable.
The present invention provides a solution to this and other problems, and offers other advantages over the prior art.